Homeostasis keeps bodies functioning well. It's the process whereby living organisms like humans control the internal environment to stay stable even when outside conditions are not.
Homeostasis helps regulate fundamental functions like body temperature. It maintains normal temperature of 37°C (98.6°F). This process regulates pH levels, keeps fluids balanced and manages electrolyte concentrations.
The term "homeostasis" is introduced by physiologist Walter Cannon in the early 20th century. Cannon suggests the body uses feedback mechanisms to adjust to both internal and external pressures.
Homeostasis disruption cause ailments from low energy levels to organ failure. People deal with changes daily, such as temperature and humidity, diet variations and stress factors. Homeostasis helps humans adapt.
For instance, during exercise, body temperature rises. The hypothalamus detects this change and triggers sweating to cool down. Without the body’s cooling system it would overheat and perish.
Functions of homeostasis include:
Body Temperature: Maintains a constant core temperature for enzyme function and cell survival.
Blood Glucose Levels: Keeping the sugar levels in blood within a narrow range provides a consistent energy source.
Blood Pressure: Regulates blood pressure for adequate oxygen and nutrient delivery to tissues and organs.
pH Balance: Maintains proper acidity and alkalinity of body fluids.
Water Balance: The amount of water in the body affects cell function and electrolyte balance.
Oxygen and Carbon Dioxide Levels: Ensures adequate oxygen supply and removal of carbon dioxide.
How Homeostasis Works
Homeostasis relies on a network of feedback loops. The loops involve three main components:
Receptor: A type of sensor, this component detects changes in the internal environment.
Control Center: This component receives information from the receptor and determines the appropriate response. The brain is a significant control center.
Effector: This component can be a muscle, gland or organ. It carries out the response to restore the internal environment to its optimal range.
Two Types of Feedback Loops: Positive and Negative
In this context positive and negative don't mean good and bad but refer to the type of function. The common type of feedback loop is a negative feedback loop. In this scenario, the response counteracts the initial change.
For example, after a meal or snack, blood sugar levels rise. The pancreas releases insulin, facilitating glucose uptake by cells. This action reduces blood sugar back to a normal range, between 70 and 140 mg/dL.
Positive feedback loops are less common. They amplify the initial change. In childbirth for example, release of the hormone oxytocin causes uterine contractions.
These stimulate release of more oxytocin, causing stronger contractions until birth. At this point oxytocin levels drop back down.
Hormones & Nervous System
Both hormones and the nervous system help maintaining homeostasis. The endocrine system releases hormones to respond to body changes, while the nervous system manages quick action.
Hormones
Homeostasis uses hormones like insulin and cortisol. When stressed, for example, the adrenal glands release cortisol. This manages metabolism, blood sugar levels, and immune responses to handle stress effectively.
The Nervous System
The nervous system, especially the autonomic nervous system, regulates involuntary functions like heart rate and digestion. It quickly adapts these in response to internal and external changes.
GI tract microbiota can influence host immunity and preserve homeostasis by microbial interaction with the mucosal immune system. Thus it's important to keep these microbes happy and healthy.
The Failure of Homeostasis
When the body's ability for homeostasis is disrupted, health problems start to erupt. In hypertension, for instance, the body fails to regulate blood pressure effectively, causing a multitude of health problems.
Hypothyroidism and diabetes also come from hormonal imbalances and the disruption of metabolic processes. Homeostasis is strongly influenced by other factors.
These include:
Environmental Changes
Extreme temperatures or high humidity can affect homeostasis. For example, when the temperature rises above 37.8°C (100°F), risk of heat exhaustion and heatstroke increase significantly.
Lifestyle Factors
Aspects of lifestyle such as nutrient or alcohol intake, erratic exercise or fasting can affect homeostasis. Sleep deprivation impairs hormonal balance, disrupts appetite regulation and creates a domino effect.
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